Accumulators are standard components in hydraulic systems wherein a hydraulic demand momentarily exceeds a pump capacity. The fluid volume in the accumulator is replenished by the pump when the pump capacity exceeds the demands of the hydraulic system.
U.S. Pat. No. 3,004,561 illustrates a typical accumulator wherein a piston separates a container into a hydraulic chamber and a gas chamber. During periods of replenishment, hydraulic fluid acts on the piston to compress the gas by reducing the volume in the gas chamber. During periods of peak demand, the hydraulic fluid is discharged from the accumulator as the gas expands and reduces the size of the hydraulic chamber. Since the piston is in continual modulation, a seal is required to prevent leakage of the hydraulic fluid into the gas chamber. Unfortunately, after a period of time, hydraulic fluid may leak past the seals and completely fill the gas chamber to thereby eliminate the effectiveness of the accumulator. For practical purposes hydraulic fluid is not compressible. However, the hydraulic fluid responds to thermal energy by expanding to develop high internal pressure in the gas chamber. Under some conditions this high internal pressure as ruptured the housing of the accumulator.